diff --git a/src/fileio.cpp b/src/fileio.cpp
index a72950bc73..8df7a82dab 100644
--- a/src/fileio.cpp
+++ b/src/fileio.cpp
@@ -75,7 +75,7 @@ size_t FioGetPos()
  * @param slot Index of queried file.
  * @return Name of the file.
  */
-const char *FioGetFilename(uint8 slot)
+const char *FioGetFilename(uint slot)
 {
 	return _fio.shortnames[slot];
 }
@@ -112,7 +112,7 @@ static void FioRestoreFile(int slot)
  * @param slot Slot number of the new file.
  * @param pos New absolute position in the new file.
  */
-void FioSeekToFile(uint8 slot, size_t pos)
+void FioSeekToFile(uint slot, size_t pos)
 {
 	FILE *f;
 #if defined(LIMITED_FDS)
@@ -247,7 +247,7 @@ static void FioFreeHandle()
  * @param filename Name of the file at the disk.
  * @param subdir The sub directory to search this file in.
  */
-void FioOpenFile(int slot, const char *filename, Subdirectory subdir)
+void FioOpenFile(uint slot, const char *filename, Subdirectory subdir)
 {
 	FILE *f;
 
diff --git a/src/fileio_func.h b/src/fileio_func.h
index 443460b2d3..d6d943d4e1 100644
--- a/src/fileio_func.h
+++ b/src/fileio_func.h
@@ -16,14 +16,14 @@
 #include "fileio_type.h"
 
 void FioSeekTo(size_t pos, int mode);
-void FioSeekToFile(uint8 slot, size_t pos);
+void FioSeekToFile(uint slot, size_t pos);
 size_t FioGetPos();
-const char *FioGetFilename(uint8 slot);
+const char *FioGetFilename(uint slot);
 byte FioReadByte();
 uint16 FioReadWord();
 uint32 FioReadDword();
 void FioCloseAll();
-void FioOpenFile(int slot, const char *filename, Subdirectory subdir);
+void FioOpenFile(uint slot, const char *filename, Subdirectory subdir);
 void FioReadBlock(void *ptr, size_t size);
 void FioSkipBytes(int n);
 
diff --git a/src/fios.h b/src/fios.h
index 73f233f84a..c954c5c83c 100644
--- a/src/fios.h
+++ b/src/fios.h
@@ -90,8 +90,10 @@ enum FileSlots {
 	SOUND_SLOT     =  1,
 	/** First slot usable for (New)GRFs used during the game. */
 	FIRST_GRF_SLOT =  2,
+	/** Maximum number of GRFs in single-player */
+	MAX_NEWGRFS = 256,
 	/** Maximum number of slots. */
-	MAX_FILE_SLOTS = 256,
+	MAX_FILE_SLOTS = 300,
 };
 
 /** Deals with finding savegames */
diff --git a/src/network/network_gui.cpp b/src/network/network_gui.cpp
index edf34ba5f9..500c34c4cb 100644
--- a/src/network/network_gui.cpp
+++ b/src/network/network_gui.cpp
@@ -1179,7 +1179,7 @@ struct NetworkStartServerWindow : public Window {
 			}
 
 			case WID_NSS_GENERATE_GAME: // Start game
-				if ((uint) CountSelectedGRFs (_grfconfig_newgame) > NETWORK_MAX_GRF_COUNT) {
+				if (CountSelectedGRFs(_grfconfig_newgame) > NETWORK_MAX_GRF_COUNT) {
 					ShowErrorMessage(STR_NEWGRF_ERROR_TOO_MANY_NEWGRFS_LOADED, INVALID_STRING_ID, WL_ERROR);
 					break;
 				}
diff --git a/src/newgrf.cpp b/src/newgrf.cpp
index b61db5918e..65eb1d7784 100644
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -9271,7 +9271,7 @@ void LoadNewGRF(uint load_index, uint file_index, uint num_baseset)
 			if (stage == GLS_LABELSCAN) InitNewGRFFile(c);
 
 			if (!HasBit(c->flags, GCF_STATIC) && !HasBit(c->flags, GCF_SYSTEM)) {
-				if (num_non_static == NETWORK_MAX_GRF_COUNT) {
+				if ((_networking && num_non_static == NETWORK_MAX_GRF_COUNT) || slot == MAX_FILE_SLOTS) {
 					DEBUG(grf, 0, "'%s' is not loaded as the maximum number of non-static GRFs has been reached", c->filename);
 					c->status = GCS_DISABLED;
 					c->error  = new GRFError(STR_NEWGRF_ERROR_MSG_FATAL, STR_NEWGRF_ERROR_TOO_MANY_NEWGRFS_LOADED);
@@ -9314,12 +9314,13 @@ void LoadNewGRF(uint load_index, uint file_index, uint num_baseset)
 /**
  * Returns amount of user selected NewGRFs files.
  */
-int CountSelectedGRFs(GRFConfig *grfconf)
+uint CountSelectedGRFs(GRFConfig *grfconf)
 {
-	int i = 0;
+	uint i = 0;
 
 	/* Find last entry in the list */
-	for (const GRFConfig *list = grfconf; list != NULL; list = list->next, i++) {
+	for (const GRFConfig *list = grfconf; list != NULL; list = list->next) {
+		if (!HasBit(list->flags, GCF_STATIC) && !HasBit(list->flags, GCF_SYSTEM)) i++;
 	}
 	return i;
 }
diff --git a/src/newgrf.h b/src/newgrf.h
index c08b5476f8..5a8217b27f 100644
--- a/src/newgrf.h
+++ b/src/newgrf.h
@@ -194,7 +194,7 @@ bool GetGlobalVariable(byte param, uint32 *value, const GRFFile *grffile);
 
 StringID MapGRFStringID(uint32 grfid, StringID str);
 void ShowNewGRFError();
-int CountSelectedGRFs(GRFConfig *grfconf);
+uint CountSelectedGRFs(GRFConfig *grfconf);
 
 struct TemplateVehicle;
 
diff --git a/src/newgrf_gui.cpp b/src/newgrf_gui.cpp
index 6ef07deb20..adda456e87 100644
--- a/src/newgrf_gui.cpp
+++ b/src/newgrf_gui.cpp
@@ -1521,7 +1521,7 @@ private:
 			if (!HasBit((*list)->flags, GCF_STATIC)) count++;
 		}
 		if (entry == NULL) entry = list;
-		if (count >= NETWORK_MAX_GRF_COUNT) {
+		if (count >= MAX_NEWGRFS) {
 			ShowErrorMessage(STR_NEWGRF_TOO_MANY_NEWGRFS, INVALID_STRING_ID, WL_INFO);
 			return false;
 		}
diff --git a/src/saveload/afterload.cpp b/src/saveload/afterload.cpp
index 61b932e3ff..628297d1bf 100644
--- a/src/saveload/afterload.cpp
+++ b/src/saveload/afterload.cpp
@@ -741,6 +741,13 @@ bool AfterLoadGame()
 		return false;
 	}
 
+	if (_networking && CountSelectedGRFs(_grfconfig) > NETWORK_MAX_GRF_COUNT) {
+		SetSaveLoadError(STR_NEWGRF_ERROR_TOO_MANY_NEWGRFS_LOADED);
+		/* Restore the signals */
+		ResetSignalHandlers();
+		return false;
+	}
+
 	/* The value of _date_fract got divided, so make sure that old games are converted correctly. */
 	if (IsSavegameVersionBefore(11, 1) || (IsSavegameVersionBefore(147) && _date_fract > DAY_TICKS)) _date_fract /= 885;